The world’s largest society of earth scientists
has released its strongest statement yet on
climate change. The 45,000-member American
Geophysical Union (AGU) says warming must be
limited to no more than 2 °C above preindustrial
levels by cutting CO2 emissions by more than half
within this century.

The climate “is now clearly out of balance and is
warming,” the statement begins. It states
unequivocally that recent warming is caused by
humans and warns that warming of more than 2 °C
would disrupt civilization by “reducing global
agricultural productivity, causing widespread
loss of biodiversity, and-if sustained over
centuries-melting much of the Greenland ice sheet
with ensuing rise in sea level of several
meters.” The statement is the first revision of
the society’s official position on climate since
2003 and is its first to recommend policy action
to cut emissions.

“The scientific community has to assume greater
responsibility to inform the public and policy
makers in a responsible, calm way,” said AGU
president Timothy Killeen at a press conference
announcing the statement. “You can’t expect
geoscientists to create policy,” he said, “but
they can analyze it.”

Many scientific societies now have official
positions on climate change, which point to human
causes and warn with increasing intensity of dire
consequences. Statements have been issued by the
American Meteorological Society, American
Chemical Society (PDF: 39 KB), American Institute
of Physics, American Association for the
Advancement of Science (PDF: 33 KB), Engineers
Australia, and Geological Society of America, in
addition to several joint statements issued by
international science academies.

No major body representing science researchers
refutes the basic science pointing to human
influence on climate. Two professional societies,
the American Association of Petroleum Geologists
and the American Association of State
Climatologists (PDF: 88 KB) have issued
statements that recognize human influence on
climate but also point to uncertainties in future
scenarios. -ERIKA ENGELHAUPT